hi all. I have a vw polo 6n 1.0l. Im havin major problems with my coolant system. The engine warms as normal. However upon reaching normal temp it overheats rapidly but only when stationary. Once i get movin again it cools back to 90. I can only presume its the fan as it never kicks in. I have a new stat, stat housing, coolant temp sensor and radiator fan switch. Also my heaters are cold. Regardless on the length of journey. Any help much appreciated